Three-dimensional visual sensor

Abstract

Slit light is projected onto the surface of an object, the reflected light is received using a video camera and analyzed by means of an image processor to thereby determine an equation of the surface onto which the slit light is projected. Then, an image is captured through normal image taking using the video camera and a straight line (line of sight) passing through the measuring point on the object and the center of the video camera is determined. Furthermore, parameters such as an affine transformation are determined by a comparison between the image of a characteristic area F of the object and a reference image. Then, the three-dimensional position and posture of the measuring point are determined from an intersection between the line of sight and the determined surface.

1. A three-dimensional sensor comprising:
 pattern light projecting unit for projecting a slit light or a spot light onto a surface of an object; 
 a camera that captures images of the object, including a first image when the projecting unit does not project the slit light or the spot light onto the surface of the object, and a second image when the projecting unit projects the slit light or the spot light onto the surface of the object; 
 a unit determining a straight line which passes through a measuring point on the object and a specific point on said camera from the first image of the object captured by said camera; 
 a unit determining the surface of the object which includes said measuring point using the second image; 
 a unit determining a three-dimensional position of said measuring point from the straight line determined by said unit for determining a straight line and the surface determined by said unit for determining the surface; and 
 a unit calculating an amount of rotation of the object around said measuring point on a plane including said surface of the object by comparing a shape of the entire object or part of the object in the first image captured by said camera, with a prepared reference shape of the entire object or part of the object. 
 
     
     
       2. A three-dimensional visual sensor which performs a three-dimensional measurement of an object, comprising:
 a two-dimensional information acquiring unit; 
 a three-dimensional information acquiring unit; and 
 an information combining unit, wherein: 
 said two-dimensional information acquiring unit determines a position of a measuring point of said object on a two-dimensional image including said object captured by a camera, compares a reference image including a characteristic area of the object with an image of said characteristic area in said two-dimensional image and determines parameter values that describe a transformation expressing geometrical deformation with respect to said reference image provided by mapping using said camera, 
 said three-dimensional information acquiring unit receives a reflected light of a light projected by projecting unit onto said object by unit of light receiving unit to acquire three-dimensional information on an inclination of a surface on which said measuring point of said object exists and/or a distance from said camera to the surface, and 
 said information combining unit combines information acquired by said two-dimensional information acquiring unit and information acquired by said three-dimensional information acquiring unit based on calibration information of said camera and generates new three-dimensional information, by determining, in the three-dimensional space, a straight line which passes through the measuring point on said object and a specific point on said camera, and determining an intersection between said surface and said straight line based on information on said straight line and the surface on which the measuring point on said object exists. 
 
     
     
       3. The three-dimensional visual sensor according to  claim 2 , wherein said reflected light is received at a position of the light receiving unit which is the same as a position of the camera at which said two-dimensional image is captured. 
     
     
       4. The three-dimensional visual sensor according to  claim 2 , wherein said camera also serves as said light receiving unit. 
     
     
       5. The three-dimensional visual sensor according to  claim 4 , wherein said camera is mounted in a robot, and captures said two-dimensional information and said three-dimensional information at a same robot position, and the three dimensional visual sensor further comprises transforming unit for transforming the new three-dimensional information generated by said information combining unit into information expressed in a coordinate system of said robot. 
     
     
       6. The three-dimensional visual sensor according to  claim 5 , wherein said transforming unit acquires position information of said robot from said robot. 
     
     
       7. The three-dimensional visual sensor according to  claim 5 , wherein said transforming unit is provided on said robot and the new three-dimensional information generated by said information combining unit is transferred to said robot. 
     
     
       8. The three-dimensional visual sensor according to  claim 2 , wherein said information combining unit comprises:
 means for determining, in the three-dimensional space, the straight line which passes through the measuring point on said object and the specific point on said camera; and 
 means for determining, based on information on said straight line and the surface on which the measuring point on said object exists, the intersection between said surface and said straight line. 
 
     
     
       9. A three-dimensional visual sensor which performs three-dimensional measurement of an object, comprising:
 a two-dimensional information acquiring unit that determines a position of a measuring point of said object on a two-dimensional image including said object captured by a camera, compares a reference image including a characteristic area of said object with an image of said characteristic area in said two-dimensional image, and determines parameter values that describe a transformation expressing geometrical deformation with respect to said reference image provided by mapping using said camera; 
 a three-dimensional information acquiring unit that receives a reflected light of a light projected by projecting unit onto said object, by unit of light receiving unit, to acquire three-dimensional information on an inclination of a first surface which has a certain positional relationship with said measuring point on said object and/or a distance from said camera to the surface; 
 an information combining unit that combines information acquired by said two-dimensional information acquiring unit and the three-dimensional information acquired by said three-dimensional information acquiring unit based on calibration information of said camera, and generates new three-dimensional information; 
 a unit for determining a straight line in a three-dimensional space which passes through the measuring point on said object and a specific point on said camera; 
 a unit for determining, from the information on said first surface, information on a virtual second surface which has a certain positional relationship with said first surface and passes through the measuring point on said object; and 
 a unit for determining an intersection between said straight line and said second surface. 
 
     
     
       10. The three-dimensional visual sensor according to  claim 9 , wherein said reflected light is received at a position of the light receiving unit which is the same as a position of the camera at which said two-dimensional image is captured. 
     
     
       11. The three-dimensional visual sensor according to  claim 9 , wherein said camera also serves as said light receiving unit. 
     
     
       12. The three-dimensional visual sensor according to  claim 10 , wherein said camera is mounted on a robot and captures said two-dimensional information and said three-dimensional information at a same robot position, and the three-dimensional visual sensor further comprises transforming unit for transforming the new three-dimensional information generated by said information combining unit into information expressed in a coordinate system of said robot. 
     
     
       13. The three-dimensional visual sensor according to  claim 12 , wherein said transforming unit acquires position information of said robot from said robot. 
     
     
       14. The three-dimensional visual sensor according to  claim 12 , wherein said transforming unit is provided on said robot and the new three-dimensional information generated by said information combining unit is transferred to said robot. 
     
     
       15. The three-dimensional visual sensor according to  claim 2 , wherein said transformation is an affine transformation. 
     
     
       16. The three-dimensional visual sensor according to  claim 2 , wherein said transformation is a perspective transformation. 
     
     
       17. The three-dimensional visual sensor according to  claim 9 , wherein said transformation is an affine transformation. 
     
     
       18. The three-dimensional visual sensor according to  claim 9 , wherein said transformation is a perspective transformation.